There’s a scientific limit to your friend circle

Struggling to keep in touch with everyone from high school isn’t a character flaw—it’s a built-in scientific fact. That’s according to research and a newly published Wall Street Journal interview with British psychologist Robin Dunbar, who found the human brain has an upper limit of ~150 friendships (known as Dunbar’s number).

Background: The brain is the most power-hungry organ in the human body. It consumes ~20% of all energy despite making up just ~2% of body weight, an unusually wide gap among animals.

• Most of that power fuels the neocortex, the region of the brain responsible for memory, language, communication—and the delicate art of not saying the wrong thing in a group chat.
• Scientists think this oversized neocortex evolved to help humans manage complex social lives.

But even our big brains have limits

According to Dunbar, the human brain only has the capacity to maintain 150 friendships at once, with a breakdown as follows:

• 5 ride-or-dies (family, best friends)
• 10 additional close friends you see at least monthly
• 35 others in your “weekend barbecue crowd”
• 100 acquaintances that you’re happy to bump into

Bottom line: Even in the modern era of instant connectivity, Dunbar’s number still holds true. “If you look at the frequency of postings on social media, frequency of telephone calls, the frequency of face-to-face contacts, the frequency of texting, you see the same layers,” Dunbar told the WSJ.